This study investigates how married men in Ghana engage with mobile fitness applications and the relational meanings that emerge from their use. Drawing on qualitative data from focus group discussions and dyadic interviews, and guided by Self-Determination Theory, Social Exchange Theory, and the Theory of Planned Behaviour, the research reveals that fitness apps serve not merely as tools for self-discipline and health monitoring, but as relational artefacts embedded in the emotional fabric of marriage. The findings show that mobile-first fitness practices, though individually designed, often spill into conjugal life. They deepen intimacy, reinforce masculine identity, and mediate cultural expectations. Men described how app-driven fitness routines fostered emotional bonding with their spouses, while women played a central role in motivating, affirming, and negotiating the boundaries of appearance, care, and respectability. However, the relational utility of current app designs remains limited, with participants expressing a clear demand for culturally attuned and emotionally responsive features that support couple-based health journeys. By situating digital fitness use within the socio-cultural context of Ghanaian marriages, the study extends conversations on digital health beyond individual behaviour to relational wellbeing, offering critical insights for behavioural designers and app developers aiming to create more inclusive and socially intelligent technologies in emerging markets.